Yes. Silence is okay! When most people are asked a question, they feel the urge to quickly respond. It’s okay to take time and collect your thoughts.
The other day, I was asked a question in class I was unsure about. Instead of saying “uhhhhm, I don’t know,” I leaned back, didn’t utter a single sound, and answered maybe 10 seconds later. The professor could tell I was taking the time; she respected that and waited for my answer.